[XeTeX] Problem with font features in tables

[Michael Lynch]

Hello,

I'm using XeTeX 3.141592-2.2-0.997, installed with MiKTeX 2.7 on Windows
Vista SP1.

I've created two styles that I'd like to use: the first, intended to be used
for abbreviations and acronyms, is defined as follows:

\newcommand{\abbracr}[ 1
]{{\addfontfeatures{LetterSpace=5.0,Letters=SmallCaps}\MakeTextLowercase{#1}
}}

The second, to be used in some headings, should make the text upper case and
select lining figures:

\newcommand{\fullcaps}[ 1
]{{\addfontfeatures{Letters=Uppercase,Numbers=Uppercase}\MakeTextUppercase{#
1}}}

These both seem to work fine, particularly when used in body text.

However, for my document, they are both used for the first time in a table.
The problem occurs when my "fullcaps" command has not been used in the body
text first. If I run it on my sample document (Test.tex), it does not
produce "full caps" numerals as I'd expect. If however, I include a
\phantom{\fullcaps{}} command prior to the first table, it works as I'd
like! This isn't a problem to do, and seems to have no effect on the final
layout, but I wondered if anyone could explain why it does this?

TestCommented.pdf is produced when I comment out the \phantom command,
whereas TestUncommented.pdf is the result of leaving it in.

I'm fairly new to XeTeX, so it's possible I'm falling foul of some detail,
but having looked through the fontspec manual, I still have no idea why this
happens, and at the very least, it does seem rather illogical. I hope this
is enough by way of explanation - if there's anything else that can help
explain why this is happening, please let me know.

Thanks,

Michael
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